News Release

New facility expected to clarify ecosystem responses to climate change

OAK RIDGE, Tenn.,
Feb. 5, 2010

Scientists hope to get a glimpse of the future with a proposed experiment facility in northern Minnesota that would allow them to adjust temperatures and levels of carbon dioxide across a broad range of possibilities projected by climate models.

Researchers believe that the experimental facility, proposed to be built in a high-carbon spruce bog within the Chippewa National Forest, would provide answers to key questions about the effects climate change could have on vegetation and ecosystems while addressing critical uncertainties related to the carbon cycle. Researchers at the Department of Energy's Oak Ridge National Laboratory, working in cooperation with the Department of Agriculture, are hopeful that construction of the facility could begin in December 2011.

Scientists are calling the multi-year experiment SPRUCE, which stands for Spruce and Peatland Responses Under Climatic and Environmental change. The carefully selected 20-acre site is located in a representative black spruce bog forest about 25 miles from Grand Rapids in the Forest Service Northern Research Station's Marcell Experimental Forest.

"The experimental site includes an ecosystem considered especially vulnerable to climate change and thought to be near its tipping point with respect to logical projections of climate change," said Paul Hanson, a member of ORNL's Environmental Sciences Division and the lead researcher for the project.

Researchers expect responses to warming and interactions with increased atmospheric carbon dioxide concentration to have important feedbacks on the atmosphere and climate because of the high carbon stocks harbored by such ecosystems.

"Our approach includes developing and performing experiments that expose critical ecosystems and their components to a broad range of temperature increases - both above and below ground - combined with atmospheric carbon dioxide enrichment," Hanson said.

To make this possible, ORNL and Forest Service researchers have proposed to design and build a system of open-top enclosures featuring recirculating forced-air heaters with internal air mixing to provide above-ground heating plus below-ground heating units. The facility would allow scientists to increase the temperature from ambient conditions to plus-9 degrees Celsius and boost carbon dioxide levels to between 800 parts per million and 900 ppm, which is at least two times ambient levels.

Hanson and colleagues are looking forward to gaining valuable insight from the experiment and a wide range of measurements that would be conducted over a 10-year period of manipulations.

"Recent workshops hosted or requested by the Department of Energy have emphasized that flagship experiments are needed to simultaneously address multiple science questions, engage a broad cross section of the scientific community and create a more visible and exciting presence to enhance DOE's important role in climate change research," Hanson said. "ORNL experiments will fill this role."

Hanson and colleagues see SPRUCE and similar facilities as being essential for the production of flexible scientific results covering a range of possible futures. This information is needed to allow scientists to develop ecological forecasting tools for policy makers to evaluate the consequences of greenhouse gases and their effects on global and regional climates. These objectives complement DOE's mandate to understand the consequences of atmospheric and climatic change for important ecosystems and the feedbacks between ecosystem response and climate.

Questions the project hopes to answer include:

How vulnerable are terrestrial ecosystems and their component organisms to atmospheric and climatic change?

What are the critical air and soil temperature response functions for ecosystem processes and their constituent organisms? Do those response functions for ecosystem processes depend on shifts in species interactions and composition?

Will full below-ground warming release unexpected amounts of carbon dioxide and methane from high-carbon-content northern forests?

To what degree will changes in plant physiology under elevated carbon dioxide impact a species' sensitivity to climate or competitive capacity within the community?

Will ecosystem services such as biogeochemical, hydrological or societal be compromised or enhanced by atmospheric and climatic change?

In preparation for the proposed research, a team from ORNL and the Forest Service will conduct the appropriate National Environmental Policy Act reviews to meet federal guidelines and inform the public about the nature of the experiment.

"We anticipate that the completed SPRUCE experimental facility will be a focus area for science conducted by investigators from the DOE national laboratories, Forest Service and independent universities," Hanson said.

The project is supported by the DOE Office of Science.

ORNL is managed by UT-Battelle for the U.S. Department of Energy Office of Science.